V40 wheel arch inserts - corrosion traps?

[anton differing]

Hello, I acquried a V40CC in September and I notice that the rear wheel arches have inserts made of what appears to be a stiff felt, presumably to absorb stones thrown up by the tyres. What concerns me, however, is that these are not a tight fit - there are gaps through which road muck and salt in winter could pass and accumulate, providing, it seems to me, the possibility for long-term corrosion.

Any thoughts on this, or am I worrying unnecessarily?

[Ninja59]

Technically speaking it could be worse if held against the metal as the dampness will then be held against the metal and lead to further corrosion.

The easiest way to avoid it is to remove the liners themselves and use a dinitrol or bilt hamber dynax product between the metal and the liner ensure plenty goes where the liner meets the arch itself.

[anton differing]

Originally Posted by Ninja59

Technically speaking it could be worse if held against the metal as the dampness will then be held against the metal and lead to further corrosion.

The easiest way to avoid it is to remove the liners themselves and use a dinitrol or bilt hamber dynax product between the metal and the liner ensure plenty goes where the liner meets the arch itself.

Thanks, but if there were no way in and the liner were suitably waterproof, it would be no problem. Other manufacturers use a thick mastic that retains it elasticity - this takes both stone punishment and acts as a sound deadener. Not sure why Volvo, which has a reputation for durability, hasn't used this approach. Cost paring?

[RoyMacDonald]

All my Volvos have had wheel arches for the last 34 years (Long before most other manufacturers) and I've never had any rust problems caused by them. Extra Dinitrol never goes amiss though if you want to give it a little more TLC.

It's normal practice for Volvo to ventilate them since 1991 or thereabouts by the way. Since they started using zinc plated steel bodies.

Maybe I should add my 1984 245 is still running strong.

[Rooster]

I think they use them rather than plastic as a first line of sound deadening from then wheel noise,

I think alot of modern cars die of electrical failure or become uneconomical to repair long before the bodys corrode

[RoyMacDonald]

Originally Posted by anton differing

Thanks, but if there were no way in and the liner were suitably waterproof, it would be no problem. Other manufacturers use a thick mastic that retains it elasticity - this takes both stone punishment and acts as a sound deadener. Not sure why Volvo, which has a reputation for durability, hasn't used this approach. Cost paring?

Wheel arch protectors have always worked better than underseal. British Leyland always used underseal! I switched to Volvo after getting sick of body rot. If the arches were closed off completely (not possible) they would still suffer from condensation causing rust. Hence the reason they are ventilated.

I don't think they are made of felt by the way. Looks like some kind of recycled plastic to me. Manufacturers have recycle their old cars now.

I have bought aftermarket wheel arch protectors for cars that didn't have them in the far distant past.

[anton differing]

Originally Posted by RoyMacDonald

Wheel arch protectors have always worked better than underseal. British Leyland always used underseal! I switched to Volvo after getting sick of body rot. If the arches were closed off completely (not possible) they would still suffer from condensation causing rust. Hence the reason they are ventilated.

I don't think they are made of felt by the way. Looks like some kind of recycled plastic to me. Manufacturers have recycle their old cars now.

I have bought aftermarket wheel arch protectors for cars that didn't have them in the far distant past.

Thanks, Roy. It depends very much on the underseal. A good one will retain its elasticity and not go hard and crack, letting water and air in.

Nobody can say that Volvo doesn't answer customers' questions. I posed the question to Volvo UK, purely because I wasn't sure that the local dealer could handle technical questions in English. I got a nice mail from Volvo UK, who said that, because it hadn't sold the car, it couldn't answer, but it referred it to Sweden, which in turn referred it to Volvo Schweiz, which said it would make sure I got an answer in English.

So, I visited the dealer and they were ready for me. I pointed out what I saw as a problem, and they said that they coat the wheel arch behind the liner with a waterproof wax compound, and therefore that anything getting past the liner would cause no problems.

Your point about ventilation is a good one. However, I was concerned about dirt and salt getting past the liners - they would most certainly not evaporate, but potentially accumulate and provide nuclei for future corrosion. The wax would certainly keep it at bay, but even silicone-based waxes harden over time and crack. Hopefully by then I'll be past caring!

[RoyMacDonald]

Originally Posted by anton differing

Thanks, Roy. It depends very much on the underseal. A good one will retain its elasticity and not go hard and crack, letting water and air in.

Nobody can say that Volvo doesn't answer customers' questions. I posed the question to Volvo UK, purely because I wasn't sure that the local dealer could handle technical questions in English. I got a nice mail from Volvo UK, who said that, because it hadn't sold the car, it couldn't answer, but it referred it to Sweden, which in turn referred it to Volvo Schweiz, which said it would make sure I got an answer in English.

So, I visited the dealer and they were ready for me. I pointed out what I saw as a problem, and they said that they coat the wheel arch behind the liner with a waterproof wax compound, and therefore that anything getting past the liner would cause no problems.

Your point about ventilation is a good one. However, I was concerned about dirt and salt getting past the liners - they would most certainly not evaporate, but potentially accumulate and provide nuclei for future corrosion. The wax would certainly keep it at bay, but even silicone-based waxes harden over time and crack. Hopefully by then I'll be past caring!

Volvo use Dinitrol. The right type for each situation. There is a thick black underseal one they use on the underbody. Modern Volvo's do not rust. I've seen Audi's and Mercs rust but never a Volvo.

[Ninja59]

Originally Posted by RoyMacDonald

Volvo use Dinitrol. The right type for each situation. There is a thick black underseal one they use on the underbody. Modern Volvo's do not rust. I've seen Audi's and Mercs rust but never a Volvo.

It depends how define "rust" as I can definitely say I have seen rust developing on the rear of the chassis legs of our previous C30 where the underseal completely failed - no accidents or incidents (as we had it from new) the car never saw a bodyshop either.

Looking at it from memory though this looked more to be developing inside out which would imply a lack of cavity protection, but either way in parts the rear of the car was lovely and brown.

Stating that they do not rust is a bit of a cop out I feel, additionally with all of the undertrays and covers in place it is not always obvious what could be lurking behind them.

I do have experience with dinitrol but as any underseal if not applied correctly it is useless - apply it over dirt or dampness it will just worsen the problem rather than preventing it.

[anton differing]

Originally Posted by Ninja59

Looking at it from memory though this looked more to be developing inside out which would imply a lack of cavity protection, but either way in parts the rear of the car was lovely and brown.

That's the stuff you've really got to worry about. Surface rust is unsightly, but rarely problematic. But when surfaces start to bubble, you know there's a major mess under there.

I'm particularly conscious of the rust problem, because we lost our previous car to rust. It was a '94 Opel Astra Caravan, and it was a mighty machine, serving us faithfully for over 20 years and 346,000Km. But the rust got it - repairing it would have cost something like 10 times the car's actual value.

We now have this gorgeous V40CC and we want it to last as long as possible!